The screensaver feature should kick in about 20 minutes of continuous play where no buttons are pushed. It's good to be aware of this for a plasma, however there is no way to activate the screensaver.
I just purchased a BD-P1600 and I got it because of the Pandora featue. However my TV is a plasma display and when I use Pandora I do not get a screensaver. I am worried that I would get burn in characters on my plasma. I looked for a screensaver feature on the menu but I could not find one. Any advice??